This invention relates to a color video endoscope system, and in particular to an endoscope system in which the control unit is capable of operation with different image sensors and various types of endoscopes.
Various color video endoscope systems are described in U.S. Pat. No. 4,253,447 to Moore and U.S. Pat. No. 4,074,306 to Kakinuma. Such systems include a control unit which generates alternating fields of red, green, and blue light. The light is directed through a fiber optic light guide within a separate endoscope section which plugs into the control unit and which has a viewing head for insertion into the cavity to be viewed. The light reflected from the cavity into which the viewing head is inserted is received by a solid state image sensor in the viewing head. The image sensor transmits an electrical signal back to the control unit. The signal is divided into its separate red, green, and blue (RGB) components by the control unit and then later merged into a composite video signal compatible with a monitor or standard television receiver. In general, such conventional color video endoscope systems are integral units in that specific circuitry in the control unit for triggering the image sensor and for optimizing the output signal from the image sensor is matched with the specific characteristics of the image sensor and type of endoscope.
Such systems have inherent disadvantages, the primary one being that if a different type of endoscope is used or if the image sensor is replaced, the circuitry in the control unit must be readjusted to optimize performance. In addition, because such color video endoscope systems generate color fields which immediately follow one another, an image of one color incident on the image sensor is immediately followed by an image of another color. Complex circuitry is required in the control unit to modify the output signal from the image sensor in order to match the levels of the successive color fields, and to obtain the necessary "grey-scale" balance.